Chain-grate stoker



June 5, 1928. 1 ,672,563

A. G. FOX Y CHAIN GRATE STOKER Filed Jan. 24, 1924 v :5 Sheets-She'et.

Fig. 1

18 INVENTOVR ATTORNEYS.

A. G. FOX

iCHAIN GRATE STOKER June 5, 1928. v V 1,672,563

Filed Jan. 24, 1924 s Sheets-Sheet 2 Fig. .3-

INVENTOR W/i l -Sm ATTORNEYS.

June 5, 1928.

A. G. FOX

CHAIN GRATE STOKER- Filed Jan. 24, 1924 3 Sheets-Sheet 3 ATTORNEYS.

Patented June 5, 1928.

UNITED STATES PATENT oFFice.

:AIJIBIED FOX, LONDON, ENGLAND, ASSIGNOB TO THE EBABCOCK WIIJCOX CGEIIQANI, OF BAYONNE, NEW JERSEY, A OORBORATION 01 NEW JERSEY.

cannon-TE s'roxna.

Application .filefi January 2'4, 1924, Serial 1M0. 688,122, and in Great Britain January 27, 1928.

to chain grate stokers My invention relates I pp iand more particularly to means for ing forced draft to such stokers.

' My invention will best :be understood by 6 reference to the following description taken with the annexed drawings, in which i Fig. 1 is .a View in vertical longitudinal section 0% a furnace installation containing an illustrative embodiment of my invention, the "section being taken on the line 11 of Fig. '2 except for the valve :at the left of Fig. 1 which is a section taken on the line 1"'=" of Fig. 2-;

Fig. 2 is 'a view in section taken on line 1 2- 2 0'1 Fig. 1;

Fig. '3 is a view chiefly in longitudinal section of a modified form "taken on the line 3-53 of Fig. '4';

Fig. .4: is a view in section taken on line of Fig. 3;

l-Fig. '5 is a side elevation of anarrangement similar to that shown. in Fig. 3, with a large part of Fig. 5 insertion on the line '55 of ZF ig. 6 and with part "of the 'chain grate hroken awayto show a sprocket wheel; .6 is a plan view of the arrangement shown fill-Fig. '5 with the chain grate removed. I

Referring to Figs. =1 'and12, "10 denotes a .30 chain gmtew'liichinthe form .therein shown is provided with 'a conduit 11 at one side of the grate for supplying forced draft thereto. The air from conduit 11 is ffed be- .neath the grate linto aplura lity of transverse boxes 12 oomnruni'cating with saidconduift by means of ducts 13. For the purpose of cdllecting solid particles of ash and fuel whiehssiit dhro "h thegrate,the'dralitfboxes 12 are provided with downwardly converging sides, as shown, terminating in arcsh'ap'ed {guides or ivalve seats 14, providing upper openings I53 and lower openings '12. In "the valve seats thus formed are "lo'caterl substantially cylin-dr'rc "l, hollow drums or 5 valves 15 having slots '16 extending along them. For 'siibstantialiy continuous opera- *tion of valves '15 I preferably "provide at 'ea'h end thereof sprocket wheels 17, the teeth of which "mesh with links 18 :of the underside (if chain grate l0. Tt will 'thus "he seen that th'e valve 15 will be given 'a con- 'tinuous :rota'tion during the operation of the grate and that whenever a slot 16 moves into .rmgis'ter with slot 12 of the valve seat M .lAfit willmeceive archarge of thesolid parmoved into register *riddlings, which have sifted and when said slot is with :slot or opening 12 the material will be discharged therethrough, without, however, the "forced draft at any time. "having an opportunity to escape through the valve opening.

' In Figs. 3' and 4 I have shown a *somewhat modified form particularly adapted for use in grates of considerable width and which would necessitate unduly long valves 15, or wherethere would be insuflicient space for the location of a conduit 11 at the side off the grate.

In the embodiment shown i[ provide a transverse an conduit 20 which communicates with a central longitudinal duct 21-, preferably of triangular, cross section, the sides of the triangle-diverging downwardly, as shown. Communicating with long'itud-L nal duct "21. are a plurality of cross ducts 22, whichifin'tunn communicate with transverse drart t boxes 23 having downwardly converging sides 28, as in the previous embodiment. The sides 23 terminate in the valve seats 14 provided with, 'Valves 15' similar to valves 14 :and 1'5,above described, and which are operated by sprocket wheels 17, the teeth of which mesh with links 18' oi? the underrun {of chain grate 10'. i The operation of valves 15 same as that 055 valves 15, above described.

The draft box 23 at the left of Fig. 3 "commimicates with the transverse conduit "2'0 and the remaining draft boxes23 communicate with cross ducts 22,-the openings preferably having valves or dampers 24, the position of which may be adjusted as shown, to control the amount of forced draft delivered to dillerent portions of the grate. 'By this arrangement thelength o'f'the valves is kept within practicable limits, the air is more evenly distributed, and in addition, the "solid particles'sift ing through the grate are prevented from falling into and choking up the main airconduit 21'. It will also be noted that by making the conduit 21 of subti'cles, or through the grate,

.Stantiallly triangular cross section with the sides diverging downwardly, the minimum amount of area 'of'the chain grate is "sealed off against the ingress of air,-whilethe conduit can be made of substantial capacity.

In Figs. 5 and 6 I have illustrated a slightly modified form in which the essential fea- :turesof the "last described modification are is in all ".respects the preserved, but which is particularly adapted to grates in which the width is not excessive.

In this construction a transverse draft con.-

duit communicates with a central, longitudinal duct 21, preferably of triangular portions 30 in which the solid particles sifting through the grate collect, each of which is provided with a valve 15* and attendant operating mechanism,;the same as described for the previous embodiments. The walls of draft box 28 converge toward the valve 15 at the bottom of the box.

In forced draft furnaces employing chain grates as commonly used, difliculties arise in supplying forced draft particularly in the case of wide and inside grates; in the case of Wide grates when the air under pressure is, brought in at the sides as is usual, it is difiicult to cause it to be supplied evenly over the entire surface of the grate. This is particularly so in the case of middle portions of the grate where a proper supply of draft ismore necessary thanit is at the side. In the case of inside grates, moreover, the sides are often too restricted to allow outside ducts. Furthermore, a substantial. obstacle to the efficient design of draft box has been that small particles of solid matter consisting of burned or unburned fuel or riddlings' pass through the apertures in the grate and choke up the draft passages unless special means be taken to remove them as fast as they collect.

It will be seen that I have provided simple and eficient means for overcoming the above-mentioned difficulties,-and that I have provided means operated by the movement of the grate itself for continuously removing the solid particles as fast as they collect.

Moreover, I have provided a special arrangement of air ducts which provide an efficient distribution of forced draft whether located within or without the Stoker. In the former case it will be seen thatI have in addition provided means whereby the distribution of the draft may be accurately controlled and the amount supplied to different parts of the grate diminished or increased as may be required.

I claim:

1. In a chain grate stoker, a plurality of draft boxes between the upper and lower runs of the grate, a conduit supplying draft to said boxes, said boxes receiving solid particles sifting through the grate and shaped so as to collect such particles in a lower portion of each box, valves in said portions permitting discharge of said particles while maintaining a seal against the escape of air from the boxes, and means cooperating with said grate for operating said valves.

2. In a chain grate stoker, a plurality of draft boxes between the upper and lower runs of the grate, a conduit supplying draft to said boxes, said boxes receiving solid particles sifting through the grate and shaped so as to collect such particles in a lower portion of each box, rotary valves in said portions permitting discharge of said particles while maintaining a seal against the escape of air from the boxes, and means cooperating with said grate for operating'said valves comprising a. sprocket wheel foreach valve meshing with the links of the chain grate.

3. In a chain grate stoker, a plurality of transverse draft boxes between the upper and lower runs of the grate. each of said boxes being open at the topto receive solid particles sifting throughthe upper run of the grate and having its sides converging downward to collect such particles in the lower narrow part of the box, and each box having a valve in its bottom arranged to permit discharge of such. particles onto the lower run of the grate while maintaining a seal against the escape of air from the box, and a conduit supplying draft to said boxes. i

4:. In a chain grate stoker, a longitudinal, substantially central draft conduit beneath the upper run of the grate, transverse draft boxes 011 each side of said conduit and communicating therewith, eachof said boxes being open at the top to receive solid particles sifting through the upper run ofthe grate and having its: sides converging downward to collect such particles in the lower narrow part of the box, and each box having a valve in its bottom arranged to permit discharge of such particles onto the lower run of the grate while maintaining a seal against the escape of air from the box, and a conduit supplying draft to said boxes.

5. In a. chain grate stoker, a longitudinal, substantially central draft conduit beneath the upper run of the grate, transverse draft boxes: on each side of said conduit and communicating therewith, each of said boxes being open at the top to receive solid particles sifting through the upper run of the grate, and having'its sides converging downward to collect such particles in the lower narrower part of the box, each box having an opening in one of its converging sides for the admission of the draft,and each box having a valve in its bottom arranged to permit discharge of such particlesonto the lower run of the grate while maintaining a seal ing against the escape of air from the box, and a conduit supplying draft to said boxes.

6. In a chain grate stoker, a longitudinal, substantially central draft conduit beneath the upper run of the grate, transverse draft boxes on each side of said conduit, eachof said boxes being open at the top and having its sides converging downward, the sides of adjacent draft boxes being spaced apart to form cross ducts between said boxes, the inner ends of said cross ducts communicatwith said central conduit, and each draft box having an air inlet port in one of its converging walls and communicating with one of said cross ducts.

7. In a chain grate stoker, a longitudinal, substantially central draft conduit beneath the upper run of the grate, transverse draft boxes on each side of said conduit, each of said boxes being open at the top and having its sides converging downward, the sides of adjacent draft boxes being spaced apart to form cross ducts between said boxes, the inner ends of said cross ducts communicating with said central conduit, and each draft box having an air inlet port in one of its converging walls and communicating with one of said cross ducts, and a valve in the bottom of each of said draft boxes arranged to permit discharge of such particles onto the lower run of the grate while maintaining a seal against the escape of air from the box.

8. In a chain grate stoker, a longitudinal,

substantially central draft conduit beneath the upper run of the grate, transverse dra boxes on each side of said conduit, each of said boxes being open at the top and having its sides converging downward, the sides of adjacent draft boxes being spaced apart to form cross inner ends of said cross ducts communicating with said central conduit, and each draft box having an air inlet port in one of its converging walls and communicating with one of said cross ducts, and dampers for controlling said inlet ports.

9. In a chain grate stoker, a longitudinal, substantially central draft conduit beneath the upper run of the grate, transverse draft boxes on each side of said conduit, each of said boxes being open at the top and having its sides converging downward, the sides of adjacent draft boxes being spaced apart vto form cross ducts between said boxes, the

inner ends of said cross ducts communicating with said central conduit, and each draft box having an air inlet port in one of its converging walls and communicating with one of said cross ducts, a valve in the bottom'of each of said draft boxes arranged to permit discharge of such particles onto the lower run of the grate while maintaining a seal against the escape of air from the box, and means cooperating with said grate for operating said valves.

ALFRED GEORGE Fox.

40 ducts between said boxes, the 

